Another plainclothes police officer approaches the man, then threatens him.

“You wanna go to arrested?” the officer asks.

The man walks away and attempts to cross the street, but the police officer follows him, then leads him over to a police cruiser. The plainclothes officer he can be heard telling a uniformed police officer that he is arresting the man for disorderly conduct. The plainclothes officer claims the man was blocking traffic and was “jumping up and down.”

After the police handcuff the man, they begin putting him inside the cruiser, and he begins yelling and swearing at them again.

As he yells, the uniformed police officer grabs him by the throat and appears to strangle him for several seconds before finally pushing him into the cruiser.

Several people begin yelling and the uniformed officer slaps away the hand of another person recording the incident. A shoving match erupts between the police and members of the public.

“Somebody’s gonna get shot,” the videographer yells.

The plainclothes police officer who arrested the man pulls out a baton and orders the videographer to cross the street and stand on the sidewalk. The videographer gets on the sidewalk, then the police officer walks up to him and starts pushing him, then grabs him by the wrist, and asks another police officer for a set of handcuffs to arrest him.

A woman walks up, telling the police that the videographer is her “little brother” and that she’s “taking him home.”

The video ends, leaving it unclear whether the videographer was arrested.

Attorneys for the American Civil Liberties Union of Massachusetts have told local media outlets that the arrested man's actions were protected by the First Amendment and that he shouldn't have been arrested.

The police department did not respond to a request for comment, but on Monday they confirmed to several local news outlets that they are investigating the video.

“No one has come forward to complain [about the incident], but that hasn’t stopped us from at least turning it over to Internal Affairs,” Boston Police Lieutenant Michael McCarthy told The Boston Globe.

It’s on the base of his neck. They’re trying to push him down into the police car...

— Boston Police Lieutenant Michael McCarthy

Although the department hasn't finished its investigation, that didn't stop McCarthy from insisting that the man in the video wasn't being strangled.

“It’s on the base of his neck,” McCarthy said. “They’re trying to push him down into the police car, and he continued to talk and yell. There’s no indication that there was any type of force used around his neck.”

Boston Mayor Marty Walsh also said the man was not strangled.

“If there was choking, he would not be able to speak,” Walsh said, according to The Boston Herald. “I don’t know all of the particulars, but I have spoken to the Commissioner and I will be briefed later on, but I don’t view that as choking.”

In 2014, Massachusetts passed a law aimed at stopping domestic violence which, in part, made it a separate crime to strangle someone. Under the law, a person convicted of strangulation faces up to five years in prison and a $5,000 fine. If the person causes serious bodily injury, they can face up to 10 years in prison and a $10,000 fine.

McCarthy reportedly declined to name the officer in the video.

We have a filed a public records request for the video the plainclothes police officer is seen recording with a cellphone.